1. Field of the Disclosure
The disclosure herein relates in general to processes for the catalytic isomerization between E and Z isomers of 1,2,3,3,3-pentafluoropropene (HFC-1225ye).
2. Description of Related Art
As a result of the Montreal Protocol phasing out ozone depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), industry has been working for the past few decades to find replacement refrigerants. The solution for most refrigerant producers has been the commercialization of hydrofluorocarbon (HFC) refrigerants. The new hydrofluorocarbon refrigerants, HFC-134a being the most widely used at this time, have zero ozone depletion potential and thus are not affected by the current regulatory phase out as a result of the Montreal Protocol. The production of other hydrofluorocarbons for use in applications such as solvents, blowing agents, cleaning agents, aerosol propellants, heat transfer media, dielectrics, fire extinguishants and power cycle working fluids has also been the subject of considerable interest.
There is also considerable interest in developing new refrigerants with reduced global warming potential for the mobile air-conditioning market.
HFC-1225ye, having zero ozone depletion and a low global warming potential, has been identified as a potential refrigerant. HFC-1225ye can also find use in other applications such as solvents, cleaning agents, foam blowing agents, aerosol propellants, heat transfer media, dielectrics, fire extinguishing agents, sterilants and power cycle working fluids. HFC-1225ye may also be used to make polymers. HFC-1225ye may exist as one of two configurational isomers, E or Z, which boil at different temperatures. Depending on the applications, HFC-1225ye may be preferably used as the Z-isomer or the E-isomer or a mixture thereof. It is known that Z-HFC-1225ye is thermodynamically more stable than E-HFC-1225ye.
The liquid phase SbF5 catalyzed isomerization of E-HFC-1225ye to Z-HFC-1225ye has been described by Burton et al. in Journal of Fluorine Chemistry, 44, 167-174 (1989). This article shows that the isomerization between E-HFC-1225ye and Z-HFC-1225ye is an equilibrium reaction.
There is a need for new catalytic isomerization processes for the isomerization between E-HFC-1225ye and Z-HFC-1225ye.